22 Sep
2016
22 Sep
'16
11:44 p.m.
2016-09-22 22:24 GMT+02:00 Pete Lancashire <pete at petelancashire.com>:
I would start looking at the Display DACs (Vol 2 p
2-10, and 2-11) Each
DAC consists of a 6820 PIA, then LS TTL Latches, diodes, and discrete & dip
resistor arrays. Then an OP Amp. to do the summing. Today it would all be
one IC.
In character mode these two DACs set the base position of each character,
Bring the cursor up to the top left and as you type look at the output of
the X DAC it should be a staircase, Do the same with the Return key, and
watch the Y DAC.
The Bottom of 2-11 are the DACs that are the dot positions for each
character.
Good idea. I will do this as soon as I replaced the TIP50. Well. Of course
this could be done without working display but it would be hard to
understand what is going on. Unfortunately measuring on the D/A and the
filter takes that the main board is pulled out and setup to operate outside
the machine.
Vol 1 pages 6-19, 20 , 21 and 22 describe how the DACs work
Manuals are on bitsavers
http://bitsavers.informatik.uni-stuttgart.de/pdf/tektronix/405x/
On Thu, Sep 22, 2016 at 12:19 PM, jim stephens <jwsmail at jwsss.com> wrote:
On 9/22/2016 12:08 PM, Charles Anthony wrote:
such, it
went to sendvid and sent two cookies. Probably safe.
Before the smoke escaped I recorded this short
videoclip to show the
behavior when typing on the machine and running simple PRINT/GOTO
program.
http://sendvid.com/k4s7k806
This link took me a fake virus warning honey trap.
-- Charles
Sendvid may be a honeytrap, but in lynx on linux, where i usually test